Energy transfer control adapted to a medical device system

Abstract

The disclosed invention varies the width of the energy pulses with constant frequency and constant amplitude to regulate the amount of energy transferred from an energy transmitting device placed outside a patient to an energy receiver inside the patient. The pulse width is achieved with a modulation technique, PWMT, to control the amount of energy transferred from the external energy transmitting coil in the system to the implanted receiver. The PWMT is used to digitally vary the amount of power from the power amplifier that drives the transmitting coil. Compared to previous analog systems a PWM system is a great deal more efficient and can easily be controlled from a digital domain system such as a microprocessor.

What is claimed is: 
     
       1. An apparatus adapted to transmit wireless energy from an external energy transmitting device placed externally to a human body to an internal energy receiver placed internally in the human body, the apparatus comprising, a first electric circuit to supply electrical pulses to the external transmitting device, said electrical pulses having leading and trailing edges, said external transmitting device adapted to transmit wireless energy placed externally to a human body to an internal energy receiver placed internally in the human body, wherein 
       the first electrical circuit being adapted to vary the lengths of first time intervals between successive leading and trailing edges of the electrical pulses and/or the lengths of 
       second time intervals between successive trailing and leading edges of the electrical pulses, and wherein 
       the transmitted wireless energy, generated from the electrical pulses having a varied power, the power depending on the lengths of the first and/or second time intervals, wherein
 the first electric circuit has a time constant, and 
 the first electric circuit is adapted to provide the electrical pulses varying the first and second time intervals to have lengths in the range of, that are in the magnitude of order of or are shorter than, the first time constant, and a relationship or proportion between the lengths of the first and second time intervals is varied, whereby, by the varying a varying power is transmitted. 
 
     
     
       2. The apparatus of  claim 1 , wherein
 the first electric circuit is adapted to provide the electrical pulses so that 
 for first and/or second time intervals having lengths that are relatively long compared to the first time constant, in the magnitude of order of the first time constant, wherein at least one of; 
 for first time intervals having lengths that are long compared to the first time constant and second time intervals having adapted lengths shorter than the lengths of the first time intervals, adapted lengths that are in the range of, particularly are in the magnitude of order of or are shorter than, the first time constant, 
 for second time intervals having lengths that are long compared to the first time constant and first time intervals having adapted lengths shorter than the lengths of the first time intervals, adapted lengths that are in the range of, particularly are in the magnitude of order of or are shorter than, the first time constant, or 
 for first and second time intervals both having adapted lengths, that are in the range of, particularly are in the magnitude of order of or are shorter than, the first time constant, and 
 
       by varying the lengths of the first and/or second time intervals in the range from lengths relatively long compared to the time constant in the magnitude of order of the first time constant to shorter lengths, a varying power is transmitted. 
     
     
       3. The apparatus according to  claim 1 , wherein
 the first electric circuit includes a receiving portion or receiving terminal receiving 
 
       feedback information transmitted from the internal energy receiver, the wireless feedback information related to the level of the power of the transmitted wireless energy as received by the receiver, and
 the first electric circuit is adapted to vary the first and second time intervals to vary the transmitted power in response to said feedback information. 
 
     
     
       4. The apparatus according to  claim 1 , wherein the amount of energy emitted from the external energy source transmitting device is regulated by an external control unit, Wherein this process is repeated intermittently at intervals during ongoing energy transfer, in the preferred embodiment many times per second, and/or executed on a more or less continuous basis during the energy transfer. 
     
     
       5. The apparatus according to  claim 1 , wherein when electrical pulses are applied, the electrical pulses remain unchanged, except for varying the first and/or second time intervals. 
     
     
       6. The apparatus according to  claim 1 , wherein the first electrical circuit is adapted to keep at least one of; the frequency of the electrical pulses substantial constant when the first and/or second time intervals are varied and the amplitude of the electrical pulses substantial constant when the first and/or second time intervals are varied. 
     
     
       7. The apparatus according to  claim 1 , further adapted to:
 supply a train of two or more electrical pulses in a row, wherein when applying the train of pulses, said train has a first electrical pulse at the start of the pulse train and has a second electrical pulse at the end of the pulse train, and 
 supply two or more pulse trains in a row, wherein the lengths of the second time intervals between successive trailing edge of the second electrical pulse in a first pulse train and leading edge of the first electrical pulse of a second pulse train are varied. 
 
     
     
       8. The apparatus according to  claim 1 , adapted to according to at least one of: a) regulate an output power from an amplifier by repetitive switching the power on and off, and
 b) supply a train of two or more electrical pulses in a row, wherein when applying the train of pulses, said train has a first electrical pulse at the start of the pulse train and has a second electrical pulse at the end of the pulse train, and 
 supply two or more pulse train in a row, wherein the lengths of the second time intervals between successive trailing edge of the second electrical pulse in a first pulse train and leading edge of the first electrical pulse of a second pulse train are varied, 
 
       wherein the apparatus is further adapted to switch a continuous pulse train off during one or more pulse periods and then on again for one or more pulse periods thereby capable of adjusting the amount of power supplied to a receiving circuit. 
     
     
       9. The apparatus according to  claim 1 , comprising
 a receiver placed internally in the human body, adapted to receive resulting pulses from the transmitted wireless energy having a varied power. 
 
     
     
       10. The apparatus according to  claim 9 , further adapted to supply the energy received by the internal energy receiver to a medical device with at least one of;
 at least one constant voltage, wherein the constant voltage is created by a constant voltage circuitry, and 
 at least one constant current, wherein the constant current is created by a constant current circuitry. 
 
     
     
       11. The apparatus according to  claim 10 , further adapted to supply the energy with at least one of;
 at least two different voltages, including the at least one constant voltage, and 
 at least two different currents including said at least one constant current. 
 
     
     
       12. The apparatus according to  claim 9 , wherein the receiver includes a second electric circuit having a second time constant, the second electric 
       circuit receiving the transmitted wireless energy as received pulses having leading and trailing edges, the second electric circuit and the second time constant adapted so that at least one of;
 the heights, amplitudes or intensifies of the received pulses are varied, 
 the frequency of the received pulses are varied, 
 by said varying of the first time intervals and/or of the second time intervals, the length of third time intervals between successive leading and trailing edges and/or of fourth time 
 intervals between successive trailing and leading edges, respectively, of the received pulses are varied, wherein the second electric circuit and the second time constant are adapted so that shorter lengths of the third time intervals give a lower output power and greater lengths of the fourth time intervals give a lower output power, 
 when varying the first time intervals and/or of the second time intervals a varying of the length of third time intervals between successive leading and trailing edges and/or of 
 
       fourth time intervals between successive trailing and leading edges, respectively, of the received pulses are only in the range of the second time constant, so that when the lengths of the first and/or second time intervals are varied, the received energy are varied and/or at least one of; the heights, amplitudes or intensities and frequency of the received pulses are varied, wherein time intervals, at least one of; 
       for third time intervals having lengths that are relatively long compared to the second time constant, in the magnitude of order of the second time constant, and fourth time intervals having adapted lengths shorter than the lengths of the third time intervals, in particular adapted lengths that are in the range of, particularly are in the magnitude of order of or are shorter than, the second time constant, 
       for fourth time intervals having lengths that are relatively long compared to the second time constant, in the magnitude of order of the second time constant, and third time intervals having adapted lengths shorter than the lengths of the fourth time intervals, in particular adapted lengths that are in the range of, particularly are in the magnitude of order of or are shorter than, the second time constant, 
       for third and fourth time intervals both having adapted lengths, in particular adapted lengths that are in the range of, particularly are in the magnitude of order of or are shorter than, the second time constant, and
 whereby by the varying of the lengths of the first and/or of second time intervals in all cases, a varying power is received by the receiver. 
 
     
     
       13. The apparatus according to  claim 9 , wherein
 the receiver including a second electric circuit adapted to receive the transmitted wireless energy as received pulses, the second electric circuit having a second time constant, and 
 the second electric circuit including a second time constant control device adapted to vary the second time constant to make the received wireless energy varied. 
 
     
     
       14. The apparatus according to  claim 1 , further adapted to transmit the wireless energy inductively from a primary coil in the external energy transmitting device to a secondary coil in the internal energy receiver. 
     
     
       15. The apparatus according to  claim 1 , wherein the apparatus is adapted to;
 when the lengths of the first time intervals are reduced, reduce the energy transmission over external transmitting device or the first coil, wherein 
 when the lengths of the second time intervals are reduced, the resulting energy transmission over external transmitting device or the first coil is increased. 
 
     
     
       16. The apparatus according to  claim 1 , for controlling transmission of wireless energy supplied to an electrically operable medical device when implanted in a patient, comprising an internal energy receiver located inside the patient 
       for receiving said wireless energy from said external energy source located outside the patient, wherein 
       the internal energy receiver being connected to the medical device for directly or indirectly supplying received energy thereto, the apparatus being further adapted to:
 determine an energy balance between the energy received by the internal energy receiver and the energy used for the medical device, and 
 control the transmission of wireless energy from the external energy transmitting device, based on the determined energy balance, 
 have varied power depending on the lengths of the first and/or second time intervals. 
 
     
     
       17. The apparatus according to  claim 16 , further adapted to detect at least one of;
 a change in said energy balance, and control the transmission of wireless energy based on said detected energy balance change, and 
 a difference between energy received by said internal energy receiver and energy used for the medical device, and the transmission of wireless energy is controlled based 
 
       on said detected energy difference, wherein 
       the apparatus is further adapted to decrease the amount of transmitted wireless energy if at least one of;
 the detected energy balance change implies that the energy balance is increasing, or vice versa, wherein the decrease/increase of energy transmission corresponds to a detected change rate, and 
 the detected energy difference implies that the received energy is greater than the used energy, or vice versa, wherein the decrease/increase of energy transmission corresponds to the magnitude of said detected energy difference. 
 
     
     
       18. The apparatus according to  claim 16 , further adapted to at least one of;
 detect the change in the amount of consumed and/or stored energy by determining over time the derivative of a measured electrical parameter related to said amount of consumed and/or stored energy, the derivative at a first given moment corresponding to the rate of the change at the first given moment, wherein the rate of change includes the direction and speed of the change, further adapted to determine said derivative based on a detected rate of change of an electrical parameter, and 
 determine the energy balance based on a detected difference between the total amount of energy received by the internal energy receiver and the total amount of consumed and/or stored energy, said detected difference being related to the integral over time of at least one measured electrical parameter related to said energy balance, thus when plot values of said electrical parameter over time as a graph in a parameter-time diagram, said integral depends from the size of the area beneath the plotted graph, wherein said integral of the electrical parameter relates to the energy balance as an accumulated difference between the total amount of energy received by said internal energy receiver and the total amount of consumed and/or stored energy. 
 
     
     
       19. The apparatus according to  claim 1 , adapted to consume the energy used for the medical device to operate the medical device, and/or store the energy in at least one energy storage device of the medical device, wherein the energy storage device includes at least one of: rechargeable battery, an accumulator or a capacitor, wherein said apparatus is adapted to determine electrical and/or physical parameters of the medical device and/or physical parameters of the patient, and the energy is stored in the energy storage device with a storing rate which is determined based on at least one of said parameters. 
     
     
       20. The apparatus according to  claim 19 , the energy storage device comprising a first storage device and a second storage device, adapted to:
 store the energy received by the internal energy receiver in the first storage device, wherein the first storage device is adapted to be charged at a higher energy rate than the second energy storage device enabling a faster charging, and 
 supply the energy from the first storage device to the second storage device at a later stage, wherein the first storage device is adapted to be able to charge more often, having a larger life-time in terms of charging events. 
 
     
     
       21. The apparatus according to  claim 1 , comprising a medical device, comprising an energy consuming part, which may be apt least one of;
 a motor, 
 a pump, 
 a restriction device, 
 a second medical device that requires energy for its electrical operation, 
 an implantable constriction device adapted to control a flow of fluid and/or other bodily matter in a lumen formed by a tissue wall of a patient's organ for gently constricting at least one portion of the tissue wall to influence the flow in the lumen, 
 a stimulation device, and 
 a control device for controlling at least one of the previous presented. 
 
     
     
       22. The apparatus according to  claim 1 , wherein
 the first electric circuit employing a continuums square wave pulse signal with a constant frequency, wherein the width of the output pulses from a PWMT amplifier is linearly regulated. 
 
     
     
       23. The apparatus according to  claim 1 , wherein the first electric circuit is adapted to provide the electrical pulses so that said relationship or proportion between the lengths of the first and second time intervals is varied according to a sinusoidal. 
     
     
       24. The apparatus according to  claim 1 , further comprising a capacitor for stabilizing the energy received by the internal energy receiver, before the energy is supplied directly or indirectly to the medical device. 
     
     
       25. The apparatus according to  claim 1 , wherein the amount of transferred energy is regulated by using at least one PWMT in the energy source, modulating at least cure of; a voltage, a current, an amplitude, a wave frequency, and a pulse characteristic, when modulating the width of the energy pulses involving to vary at least one of said first and second time intervals.